Two of them stole the sensor from their employer Teledyne Dalsa of Waterloo, Ontario with help from a former employee, according to the Royal Canadian Mounted Police.

They then sold it to two Chinese firms, one of them state-owned, in violation of the Canadian Controlled Goods Program and other laws.

The fourth accused works for one of the Chinese companies allegedly involved in the scheme.

The microelectronics were "intended for space satellite use," the RCMP said in a statement yesterday.

"This investigation is an example of foreign governments having an interest in Canadian-based controlled technology and it highlights the RCMP's commitment to keeping Canadian's safe from the potential misuse of that technology," RCMP Superintendent Jamie Jagoe said.

The two-year probe also involved the Canadian Space Agency, the military, the US Department of Homeland Security and the FBI.

Canadians Arthur Xin Pang, 46, and Binqiao Li, 59, were arrested and charged with more than a dozen related crimes.

Meanwhile, arrest warrants have been issued for Nick Tasker, 62, of Britain, and Hugh Ciao, 50, of California, who is currently in China.